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v UNITED STATES PATENT EEinE.

FREDERICK M. HILL, OF BROOKLYN, NEW YORK.

SAFETY PAPER FOR CHECKS, DRAFTS, 8M).

EPECIFICATION forming part of Letters Patent No. 330,894, dated November24,1885.

Application filed April 18, 1885. Serial No. 162,711. (No specimens.)

.To all whom it may concern.-

Be it known that I, FREDERICK M. HILL, a citizen of the United States,residing at Brooklyn, county of Kings, and State of New York, haveinvented a certain new safety paper for the purpose of checks, drafts,bills of exchange, and other purposes; and I do hereby declare that thefollowing is a full, clear, and exact description of this new safetypaper, which will enable others skilled in the arts to which itappertains to make and use the same.

I take a mixture of ferro-cyanide of manganese and hydrated peroxide ofiron and put them into or mix them with the pulp of the paper, or I putthe said mixture partly in the pulp and partly in the sizing of thepaper; or I put the said mixture of ferro'cyanide of manganese andhydrated sesquioxide of iron into the sizing alone of the paper. Theferro cyanide of manganese is turned blue by most acids and brown bycaustic alkalies, so that an attempt to alter the writing or change thepaper by chemical action produces disoolorations in and on the paper.These chemicals above alluded to are put in the paper through theordinary means used in making paperthat is, mixed in the pulp-vat orsizing-vat, or any other equivalent means in making paper.

What I claim as new, novel, and useful in asafety paper is- Thecombination consisting of the paper or pulp or sizing, ferro-cyanide ofmanganese, and hydrated peroxide of iron, for the purposes abovementioned.

FREDERICK M. HILL.

Witnesses:

HENRY W ELLINGTON, CHAS. E. MIELKE.

